Something curious happened today...

[Leo24]

Hi guys,

From time to time I make raw dumps from my Amiga SCSI drives under PC Linux with the dd command (dd if=/dev/sdX of=dump.hdf) and use these in WinUAE because, it's hard to admit, but dealing with WinUAE is nowadays more comfortable than with a real Amiga. I usually update my AmigaOS and tools, do some time killing stuff and once the system in WinUAE evolved enough for a while, I transfer the hard disk image back to the SCSI drive into my Amiga 3000.

Last weekend I thought, hey let's install AMIX in WinUAE using the tape drive method for a correct installation. Apply all the patches and additional drivers, compile some newer commands and tools. And finally install Workbench 1.3 and 3.1 in a tripple boot configuration. (I have one of those early A3000 with SuperKickstart support). WinUAE supports this quite well and helped me to experiment with various partition sizes and limits, since Kickstart 1.4beta and AMIX are quite picky about it. All the boot partitions including UNIX_Root and UNIX_Swap must be within the first 1GB range. Partitions beyond 1GB can be only formatted and used after Kickstart 3.1 has been loaded.

Now to the curious part. Once the tripple boot image was ready, I transferred it to my Ubuntu 17.04 64bit system where I already connected the SCSI hard disk and started dumping the image back to the drive with: dd if=dump.hdf of=/dev/sdX
Then the unexpected happened. As soon as dd finished the transfer, Ubuntu Linux suddenly mounted the UNIX_Root partition from the SCSI disk and the file manager popped up with the AMIX file contents. I was WTF???...

I have many times used this method to dump images containing AOS and NetBSD partitions, but Linux never detected any of those partitions. Now for the first time I had an AMIX partition and Linux was able to detect it. Of course, I rebooted Linux and tried again and yes, Linux detects UNIX_Root at sdb3. But how??? As far as I know PC Linux does not support Amiga RDB partition tables, otherwise it would also see the other partitions on the SCSI disk albeit not able to mount it. Very very strange.

Does someone know what's going on here?

[jbl007]

Originally Posted by Leo24

As far as I know PC Linux does not support Amiga RDB partition tables

In fact the Linux kernel does support Amiga partition tables but almost all distros disable it because nobody needs this nowadays (well except us of course ). Perhaps you are lucky and the Ubuntu guys just forgot to disable it in 17.04.
What's the output of

zgrep AMIGA /proc/config.gz

?

For me it says

# CONFIG_AMIGA_PARTITION is not set

[Locutus]

Debian for example does ship with a kernel supporting RDB partition maps and FFS Filesystem modules. (Partition map support cant be built as a module by the way)

AMIX Partitions aren't Amiga FFS though but some flavour of UFS which of course Linux also supports :-)